The seasonal performance of natural gas fuel-fired heat pumps in residential space heating installations has often been relatively low. In some instances, a seasonal heating coefficient of performance of only slightly more than one can be experienced. This means that the heat pump delivers perhaps only 10 to 20% more heat to a house than the fuel value of the gas used by the heat pump. When the electrical fans and pumps associated with the gas heat pump are accounted for, it may actually cost more to operate the heat pump than a high efficiency gas furnace, boiler or hydronic water heater. The steady state coefficient of performance of a typical gas fired heat pump can be relatively high, for example, approaching the range of 1.8. It is believed that the loss of efficiency is related to cycling losses which occur when the house thermostat comes on for relatively short cycles of typically 10 to 15 minutes and then shuts off for perhaps another 15 to 20 minutes. Since the heat pump mechanism is largely outside, every time it shuts off heat runs back from the house through the piping and is dissipated outdoors. Additionally, the prime mover or engine cools off so that when restarted it sacrifices efficiency for a minute or few minutes until it warms up to a normal operating temperature.